Siphovirus long flexible non-contractile tail assembly and receptor adsorption

A morphogenetic assembly and host-entry pathway conserved across siphoviruses (long non-contractile tailed bacteriophages of class Caudoviricetes) and homologous to the inner tail-tube/baseplate-hub core of contractile myoviruses and type VI secretion systems. Assembly begins at the distal tip with the host entry-receptor attachment protein gpJ, which sequentially recruits the tail tip initiator proteins gpI, gpL (an [4Fe-4S] cluster-binding hub component), and gpK (a peptidoglycan-active NlpC/P60-domain protein) together with the tape measure protein gpH and gpM. The chaperone gpG and its programmed -1 ribosomal frameshift fusion product gpGT coat the alpha-helical tape measure protein gpH and recruit the major tail tube subunit gpV, which polymerizes into 31 to 32 stacked hexameric rings along the gpH scaffold until reaching its N-terminus. The hexameric terminator protein gpU caps the completed tube, gpH is proteolytically matured to gpH*, and the tail completion protein gpZ renders the mature tail competent to join the gpW/gpFII-plugged DNA-filled head. Optional side tail fibers (Stf, folded with the Tfa chaperone) attach to the collar/tail to mediate rapid reversible primary adsorption before irreversible gpJ engagement of the outer membrane receptor triggers gpH*-mediated DNA ejection across the host envelope.

MODULE:phage_siphovirus_tail_assemblyCOMPLETECONCRETEBiological Processmodules/phage_siphovirus_tail_assembly.yaml

viral tail assemblyGO:0098003 viral head-tail joiningGO:0098005 entry receptor-mediated virion attachment to host cellGO:0098670 symbiont genome ejection through host cell envelope, long flexible tail mechanismGO:0099001

PMID:23911548

Chaperone-protein interactions that mediate assembly of the bacteriophage lambda tail to the correct length.

Establishes the mechanism by which tail assembly chaperones gpG and gpGT bind the tape measure protein gpH and recruit major tail subunit gpV to assemble the lambda tail to its programmed length.

PMID:19251647

The phage lambda major tail protein structure reveals a common evolution for long-tailed phages and the type VI bacterial secretion system.

Resolves the structure of the phage lambda major tail tube subunit gpV and establishes the evolutionary conservation of long-tailed bacteriophage tail tubes.

GO:0098003

viral tail assembly

Defines the morphogenetic assembly of the bacteriophage tail structure.

GO:0099001

symbiont genome ejection through host cell envelope, long flexible tail mechanism

Defines genome delivery into the host cell through a long flexible non-contractile siphovirus tail.

Exemplar phage: Escherichia phage lambda (NCBITaxon:2681611). Generalizes across long non-contractile tailed phages (siphoviruses such as coliphages HK97, T5, SPP1, and mycobacteriophages) that share the distal tail tip initiator -> G/GT-chaperoned tape measure -> hexameric tail tube -> terminator assembly cascade.

7Nodes

6Parts

0Variant Sets

0Variants

12Annotons

4Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:phage_siphovirus_tail_assembly deep-research report alongside the module YAML.

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Reaction chaining (advisory)

✓ every PRECEDES step chains, or its break is acknowledged via chaining_status.

tail_tip_j_step → tail_tip_initiator_step [NOT_CHECKED]
Trimeric gpJ forms the basal hub onto which gpI, gpL, and gpK assemble in strict order.
tail_tip_initiator_step → tape_measure_chaperone_step [NOT_CHECKED]
The gpJ-gpI-gpL-gpK subcomplex recruits gpG/gpGT-coated gpH and is stabilized by gpM to form the 15S initiator.
tape_measure_chaperone_step → tail_tube_polymerization_step [NOT_CHECKED]
The gpGT frameshift chaperone recruits gpV monomers onto the initiator to polymerize along gpH.
tail_tube_polymerization_step → tail_termination_completion_step [NOT_CHECKED]
Exposure of the gpH N-terminus after 31 to 32 gpV rings recruits hexameric gpU and subsequently gpZ.

Function consistency and core coverage

11 gene-function check(s) reflected in core functions · 0 conflict(s) · 10 evidence or coverage gap(s) (21 comparison(s))

Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.

Annoton	Participant	Function	Assessment
gpj_tip_activity	J (Escherichia phage lambda) UniProtKB:P03749 Family Representative	host cell surface receptor binding GO:0046789	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpi_initiator_activity	I (Escherichia phage lambda) UniProtKB:P03730 Family Representative	structural constituent of virion GO:0039660	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpl_initiator_activity	L (Escherichia phage lambda) UniProtKB:P03738 Family Representative	4 iron, 4 sulfur cluster binding GO:0051539	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpm_initiator_activity	M (Escherichia phage lambda) UniProtKB:P03737 Family Representative	structural constituent of virion GO:0039660	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gph_tape_measure_activity	H (Escherichia phage lambda) UniProtKB:P03736 Family Representative	structural constituent of virion GO:0039660	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpg_gt_chaperone_activity	G (Escherichia phage lambda) UniProtKB:P03734 Family Representative	protein folding chaperone GO:0044183	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpg_gt_chaperone_activity	T (Escherichia phage lambda) UniProtKB:P03735 Family Representative	protein folding chaperone GO:0044183	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpv_tube_activity	V (Escherichia phage lambda) UniProtKB:P03733 Family Representative	structural constituent of virion GO:0039660	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpu_terminator_activity	U (Escherichia phage lambda) UniProtKB:P03732 Family Representative	structural constituent of virion GO:0039660	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
stf_fiber_activity	stf (Escherichia phage lambda) UniProtKB:P03764 Family Representative	structural constituent of virion GO:0039660	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
tfa_chaperone_activity	tfa (Escherichia phage lambda) UniProtKB:P03740 Family Representative	protein folding chaperone GO:0044183	Core Supported The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
gpj_tip_activity	Phage lambda host specificity tip protein J family PANTHER:PTHR36251:SF2 Family	host cell surface receptor binding GO:0046789	Family Review Missing No supported structured family review is available for PANTHER:PTHR36251:SF2.
gpi_initiator_activity	Phage lambda tail tip protein I family (InterPro:IPR010654 / Pfam:PF06805) Family	structural constituent of virion GO:0039660	Family Id Missing The family has no identifier linking it to a curated family review.
gpl_initiator_activity	Phage lambda tail tip protein L family NCBIfam:TIGR01600 Family	4 iron, 4 sulfur cluster binding GO:0051539	Family Review Missing No supported structured family review is available for NCBIfam:TIGR01600.
gpm_initiator_activity	Phage lambda minor tail tip protein M family (InterPro:IPR010265 / Pfam:PF05939) Family	structural constituent of virion GO:0039660	Family Id Missing The family has no identifier linking it to a curated family review.
gph_tape_measure_activity	Phage lambda tape measure protein H family NCBIfam:TIGR01541 Family	structural constituent of virion GO:0039660	Family Review Missing No supported structured family review is available for NCBIfam:TIGR01541.
gpg_gt_chaperone_activity	Phage tail assembly chaperone G/GT family NCBIfam:TIGR01674 Family	protein folding chaperone GO:0044183	Family Review Missing No supported structured family review is available for NCBIfam:TIGR01674.
gpv_tube_activity	Phage tail tube protein V family (InterPro:IPR032494 / Pfam:PF16461) Family	structural constituent of virion GO:0039660	Family Id Missing The family has no identifier linking it to a curated family review.
gpu_terminator_activity	Phage lambda tail terminator U family (InterPro:IPR009312 / Pfam:PF06141) Family	structural constituent of virion GO:0039660	Family Id Missing The family has no identifier linking it to a curated family review.
stf_fiber_activity	Prophage side tail fiber Stf family PANTHER:PTHR35191:SF1 Family	structural constituent of virion GO:0039660	Family Review Missing No supported structured family review is available for PANTHER:PTHR35191:SF1.
tfa_chaperone_activity	Caudovirus tail fiber assembly chaperone Tfa/gp38 family PANTHER:PTHR34413:SF2 Family	protein folding chaperone GO:0044183	Family Review Missing No supported structured family review is available for PANTHER:PTHR34413:SF2.

Gene-review completeness (13/13 grounded genes reviewed)

13 complete review(s) · 0 with deep research · 0 missing review · 13 reviewed but lacking deep research

Gene	Review	Complete	Deep research
G P03734	✓	✓	✗
H P03736	✓	✓	✗
I P03730	✓	✓	✗
J P03749	✓	✓	✗
K P03729	✓	✓	✗
L P03738	✓	✓	✗
M P03737	✓	✓	✗
stf P03764	✓	✓	✗
T P03735	✓	✓	✗
tfa P03740	✓	✓	✗
U P03732	✓	✓	✗
V P03733	✓	✓	✗
Z P03731	✓	✓	✗

Tree

Siphovirus long flexible tail assembly and receptor adsorptionBiological Processphage_siphovirus_tail_assembly

Parts
1. 1. distal tail tip nucleation and host entry receptor recognition
2. Distal tail tip nucleation and LamB receptor recognition by gpJProtein Complextail_tip_j_step
  
  Annotons
  - Tip attachment protein J Family: Phage lambda host specificity tip protein J family
3. 2. conical tail tip initiator complex assembly
4. Sequential assembly of tail tip initiator complex (gpI, gpL, gpK, gpM)Protein Complextail_tip_initiator_step
  
  Annotons
  - Tail tip assembly protein I Family: Phage lambda tail tip protein I family (InterPro:IPR010654 / Pfam:PF06805)
  - Tail tip protein L Family: Phage lambda tail tip protein L family
  - Tail tip assembly protein K Family: NlpC/P60 tail tip assembly peptidase family
  - Tail tip protein M Family: Phage lambda minor tail tip protein M family (InterPro:IPR010265 / Pfam:PF05939)
5. 3. tape measure scaffolding and chaperone-assisted recruitment
6. Tape measure protein gpH scaffolding and gpG/gpGT chaperone coatingProtein Complextape_measure_chaperone_step
  
  Annotons
  - Tape measure protein H Family: Phage lambda tape measure protein H family
  - Tail assembly chaperones G and GT Family: Phage tail assembly chaperone G/GT family
7. 4. hexameric tail tube polymerization
8. Polymerization of major tail tube subunit gpV along gpHProtein Complextail_tube_polymerization_step
  
  Annotons
  - Major tail tube protein V Family: Phage tail tube protein V family (InterPro:IPR032494 / Pfam:PF16461)
9. 5. tail tube termination and head-joining maturation
10. Tail tube termination by gpU and completion by gpZ for head-tail joiningProtein Complextail_termination_completion_step
  
  Annotons
  - Tail tube terminator protein U Family: Phage lambda tail terminator U family (InterPro:IPR009312 / Pfam:PF06141)
  - Tail completion protein Z Family: Phage lambda tail completion protein Z family (InterPro:IPR010633 / Pfam:PF06763)
11. 6. optional side tail fiber assembly and primary reversible adsorption optional
12. Chaperone-assisted assembly of Stf side tail fibers by TfaProtein Complexside_tail_fiber_step
  
  Annotons
  - Side tail fiber protein Stf Family: Prophage side tail fiber Stf family
  - Tail fiber assembly chaperone Tfa Family: Caudovirus tail fiber assembly chaperone Tfa/gp38 family

Details

Context

CaudoviricetesNCBITaxon:2731619 Escherichia phage lambdaNCBITaxon:2681611

Siphovirus long flexible tail assembly and receptor adsorptionBiological Processphage_siphovirus_tail_assembly

Context

CaudoviricetesNCBITaxon:2731619 Escherichia phage lambdaNCBITaxon:2681611

Connections

tail_tip_j_step -> tail_tip_initiator_step Precedes

tail_tip_initiator_step -> tape_measure_chaperone_step Precedes

tape_measure_chaperone_step -> tail_tube_polymerization_step Precedes

tail_tube_polymerization_step -> tail_termination_completion_step Precedes

Part 1: distal tail tip nucleation and host entry receptor recognition

Distal tail tip nucleation and LamB receptor recognition by gpJProtein Complextail_tip_j_step

Annotons

Tip attachment protein J

gpj_tip_activity

Participant: Family: Phage lambda host specificity tip protein J family

Family:

Phage lambda host specificity tip protein J familyPANTHER:PTHR36251:SF2

Representative Members: J (Escherichia phage lambda)UniProtKB:P03749

Function

host cell surface receptor bindingGO:0046789

Processes

viral tail assemblyGO:0098003 entry receptor-mediated virion attachment to host cellGO:0098670

Locations

host cell cytoplasmGO:0030430

Forms the homotrimeric distal tail fiber/tip hub that nucleates the 15S tail initiator complex during morphogenesis and mediates irreversible binding to the host outer membrane maltoporin LamB.

Part 2: conical tail tip initiator complex assembly

Sequential assembly of tail tip initiator complex (gpI, gpL, gpK, gpM)Protein Complextail_tip_initiator_step

Annotons

Tail tip assembly protein I

gpi_initiator_activity

Participant: Family: Phage lambda tail tip protein I family (InterPro:IPR010654 / Pfam:PF06805)

Family:

Phage lambda tail tip protein I family (InterPro:IPR010654 / Pfam:PF06805)

Representative Members: I (Escherichia phage lambda)UniProtKB:P03730

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

Connects the trimeric gpJ distal tip to the upper tail tip ring during initiator complex assembly.

Tail tip protein L

gpl_initiator_activity

Participant: Family: Phage lambda tail tip protein L family

Family:

Phage lambda tail tip protein L familyNCBIfam:TIGR01600

Representative Members: L (Escherichia phage lambda)UniProtKB:P03738

Function

4 iron, 4 sulfur cluster bindingGO:0051539

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

Iron-sulfur ([4Fe-4S]) cluster-binding structural protein of the conical tail tip complex.

Tail tip assembly protein K

gpk_initiator_activity

Participant: Family: NlpC/P60 tail tip assembly peptidase family

Family:

NlpC/P60 tail tip assembly peptidase familyPANTHER:PTHR34858:SF1

Representative Members: K (Escherichia phage lambda)UniProtKB:P03729

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

NlpC/P60-domain component required for tail tip initiator maturation.

Tail tip protein M

gpm_initiator_activity

Participant: Family: Phage lambda minor tail tip protein M family (InterPro:IPR010265 / Pfam:PF05939)

Family:

Phage lambda minor tail tip protein M family (InterPro:IPR010265 / Pfam:PF05939)

Representative Members: M (Escherichia phage lambda)UniProtKB:P03737

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

Stabilizes the upper ring of the tail tip initiator complex after tape measure protein gpH incorporation, forming the platform for gpV tail tube polymerization.

Part 3: tape measure scaffolding and chaperone-assisted recruitment

Tape measure protein gpH scaffolding and gpG/gpGT chaperone coatingProtein Complextape_measure_chaperone_step

Annotons

Tape measure protein H

gph_tape_measure_activity

Participant: Family: Phage lambda tape measure protein H family

Family:

Phage lambda tape measure protein H familyNCBIfam:TIGR01541

Representative Members: H (Escherichia phage lambda)UniProtKB:P03736

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003 symbiont genome ejection through host cell envelope, long flexible tail mechanismGO:0099001

Locations

host cell cytoplasmGO:0030430

Coiled-coil ruler protein that occupies the central lumen of the tail tube to specify the 31- to 32-ring (132.7 to 135 nm) tail length, undergoes C-terminal maturation to gpH*, and is extruded across the host cell envelope upon receptor binding to form the DNA ejection channel.

Tail assembly chaperones G and GT

gpg_gt_chaperone_activity

Participant: Family: Phage tail assembly chaperone G/GT family

Family:

Phage tail assembly chaperone G/GT familyNCBIfam:TIGR01674

Representative Members: G (Escherichia phage lambda)UniProtKB:P03734 T (Escherichia phage lambda)UniProtKB:P03735

Function

protein folding chaperoneGO:0044183

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

Non-structural cytoplasmic chaperones (where gpGT arises by a conserved -1 translational frameshift) that coat the extended tape measure protein gpH via the G domain and recruit monomeric gpV via the T domain to drive processive tube polymerization.

Part 4: hexameric tail tube polymerization

Polymerization of major tail tube subunit gpV along gpHProtein Complextail_tube_polymerization_step

Annotons

Major tail tube protein V

gpv_tube_activity

Participant: Family: Phage tail tube protein V family (InterPro:IPR032494 / Pfam:PF16461)

Family:

Phage tail tube protein V family (InterPro:IPR032494 / Pfam:PF16461)

Representative Members: V (Escherichia phage lambda)UniProtKB:P03733

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

Assembles into 31 to 32 stacked hexameric rings (186 to 192 subunits) around the tape measure protein gpH, displacing gpG/gpGT chaperones; its C-terminal Ig-like Big_2 domain projects outward to facilitate weak carbohydrate/surface interactions on the host cell.

Part 5: tail tube termination and head-joining maturation

Tail tube termination by gpU and completion by gpZ for head-tail joiningProtein Complextail_termination_completion_step

Annotons

Tail tube terminator protein U

gpu_terminator_activity

Participant: Family: Phage lambda tail terminator U family (InterPro:IPR009312 / Pfam:PF06141)

Family:

Phage lambda tail terminator U family (InterPro:IPR009312 / Pfam:PF06141)

Representative Members: U (Escherichia phage lambda)UniProtKB:P03732

Function

structural constituent of virionGO:0039660

Processes

viral tail assemblyGO:0098003

Locations

host cell cytoplasmGO:0030430

Hexameric ring that binds the proximal end of the 31st or 32nd gpV ring upon reaching the N-terminus of gpH, arresting further gpV polymerization.

Tail completion protein Z

gpz_completion_activity

Participant: Family: Phage lambda tail completion protein Z family (InterPro:IPR010633 / Pfam:PF06763)

Family:

Phage lambda tail completion protein Z family (InterPro:IPR010633 / Pfam:PF06763)

Representative Members: Z (Escherichia phage lambda)UniProtKB:P03731

Processes

viral tail assemblyGO:0098003 viral head-tail joiningGO:0098005

Locations

host cell cytoplasmGO:0030430

Acts on the gpU-capped tail to complete proximal maturation, enabling spontaneous attachment to the gpW/gpFII-plugged head connector and rendering the joined virion infectious.

Part 6: optional side tail fiber assembly and primary reversible adsorption (optional)

Chaperone-assisted assembly of Stf side tail fibers by TfaProtein Complexside_tail_fiber_step

Annotons

Side tail fiber protein Stf

stf_fiber_activity

Participant: Family: Prophage side tail fiber Stf family

Family:

Prophage side tail fiber Stf familyPANTHER:PTHR35191:SF1

Representative Members: stf (Escherichia phage lambda)UniProtKB:P03764

Function

structural constituent of virionGO:0039660

Processes

virus tail fiber assemblyGO:0098004 adhesion receptor-mediated virion attachment to host cellGO:0098671

Locations

host cell cytoplasmGO:0030430

Trimeric long side tail fiber present in wild-type Ur-lambda (but frameshifted in standard laboratory strain lambda PaPa) that recognizes host outer membrane OmpC to accelerate reversible primary capture.

Tail fiber assembly chaperone Tfa

tfa_chaperone_activity

Participant: Family: Caudovirus tail fiber assembly chaperone Tfa/gp38 family

Family:

Caudovirus tail fiber assembly chaperone Tfa/gp38 familyPANTHER:PTHR34413:SF2

Representative Members: tfa (Escherichia phage lambda)UniProtKB:P03740

Function

protein folding chaperoneGO:0044183

Processes

virus tail fiber assemblyGO:0098004

Locations

host cell cytoplasmGO:0030430

gp38-like cytoplasmic intramolecular/intermolecular chaperone required for folding the C-terminal receptor-binding domain of Stf.